I moved this to beyond the manual where we can freely discuss non-proof grade materials and settings.
Begin with selecting a Glowforge preset material for a thinplywood. Then manually adjust as needed or switch to thick and go up or down.
Plywood is so difficult to design for since there are so many formulations. It is notorious for having pockets of resistance that are immune to the laser.
Test and test again on a small section. But it is always good to start with Proofgrade settings and work from there.